The field of the present invention relates to a method for producing a vegetable matrix extract with a non-ionic amphiphilic compound as extraction aid in aqueous medium.
Solid-liquid extraction is the process consisting in extracting a substance present in a solid, in particular a plant, into a liquid solvent. Maceration, infusion and decoction are conventional solid-liquid extraction methods.
Solvents are liquids—at working temperature—having the property of dissolving, diluting or extracting other substances without chemically modifying said substances and without themselves being modified. They are used, in large amounts, for numerous other industrial applications (paints, detergents, coatings, phytosanitary products, etc.) and are conventionally of petrochemical origin.
However, dwindling oil reserves and stricter regulations on chemicals make it necessary to find more environmentally friendly alternatives.
Green extraction is based on the discovery and design of extraction processes that reduce energy consumption and allow the use of alternative solvents—agro-solvents—while guaranteeing safe, high-quality extracts useful as ingredients in the pharmaceuticals, cosmetics, agri-food, fine chemicals and biofuels industries (Green extraction of natural products (GENP2013), (2014), Comptes Rendus Chimie, 17, 179-180). In this context, the improvement of existing processes and the design of new processes are the subject of much work aimed at reducing the environmental impact of the extraction step, leading to the emergence and popularization of technologies such as extraction by ultrasound, microwaves, supercritical CO2 and flash vacuum-expansion. In parallel, the search for alternative extraction solvents, of non-petrochemical origin, constitutes another path to improvement.
The market for agro-solvents derived from wood, field crops (starch- or sugar-producing) and oleaginous species is thus in full expansion, leading to terpene derivatives, alcohols (ethanol, butanol, 1,3-propanediol), furfural derivatives and methyl esters (Formule Verte No. 8, December 2011, pp. 28-32).
Water is a natural solvent considered to be renewable. However, its high polarity does not allow the extraction of certain lipophilic molecules of interest.
It is thus necessary to have new solvents for extracting compounds of different ranges of polarity (increasingly wide range of polarity, or optimization of extraction of lipophilic compounds).
Certain non-ionic amphiphilic compounds in aqueous solution allow, at sufficient concentration, solubilization of lipophilic compounds.
Nicotinamide, dimethyl isosorbide, alkyl polyglycosides and urea are examples of these non-ionic amphiphilic compounds. The potential of these compounds as solubilization aids for certain lipophilic molecules in aqueous medium has been explored (Sanghvi R., Evans D., Yalkowsky S. Stacking complexation by nicotinamide: a useful way of enhancing drug solubility.
(2007) 336: 35-41).
But the solubilization property is not sufficient to allow extraction of solutes from vegetable matrix. Indeed, in the field of plant extraction, the extraction solvent must penetrate the vegetable matrix, destroy the membranes and release the compounds into the impregnation solvent (phenomena of diffusion, desorption, dissolution, etc.), and allow diffusion of the matrix solute towards the liquid film surrounding the solid, and transfer towards the solvent (limiting step). Depending on the solvent used, the plant cell membranes are weakened to a greater or lesser extent, which may or may not allow the release of the compounds contained within said cells.